Differential-pulley apparatus



W. H. THOMPSON. .Differential Pulley Apparatus.

2. .AMJ

Patented Mar.

N.FETEFI8. FHOTO-LITHOGRAPHER, WASHINBTON. D. C.

WILLIAM H. THOMPSON,

OF CLEVELAND, OHIO.

DIFFERENTIAL-PULLEY APPARATUS.

SPECIFICATION forming part of Letters Patent No. 225,953, dated March 30, 1880.

Application filed June 9, 1879 To all whom it may concern:

Be it known that I, WILLIAM H. THOMP- SON, of the city of Cleveland, in the county of Cuyahoga and State of Ohio, have invented a new and useful Improvement in Differential- Pulley Apparatus for Hoisting Purposes, which improvement is fully set forth in the following` speciflcation, reference being had to the accompanying' drawings.

The object of my invention is to construct chain hoisting-blocks that are easily movable from place to place, to be operated by handpower only, without the aid of any other sepa rate device, being complete in themselves.

Figure l of the drawings is an edge view, Fig. 2 a side view, and Fig. 3 an edge view, of the gear-wheels and chain-sheaves of the top block, apart from the block-frame and chains, of my newly-invented chain hoistingblocks.

They consist of a top double-sheaveblock, A, and a bottom single-sheave block, B, connected by an endless hoisting chain rove through them, the top block being provided at its top end with a suspending-hook, Q, and the bottom block having at its bottom end a hook, P, for attaching the mass to be lifted. They are operated, either for hoisting or lowering, by an endless hand-chain, N, on the sheave M of the top block, the gear-wheels and hoistingchain sheaves of the top block being so arranged and proportioned as to cause the two chainsheaves G H to revolve at velocities different one from the other, so that the hoisting-chain R will be wound up by one faster than it will be wound off by the other, and vice versa, according as the blocks are operated for hoisting or lowering.

The frames of the top and bottom blocks should be constructed so as to form guards K K for the hoisting-chain and L L for the handchain for retaining the chains upon their respective sheaves.

The two hoisting-chain sheaves G H of the top block, A, are of equal diameter, and grooved and recessed upon their periphery to fit the links and pitch of the hoisting-chain It, and so as to prevent the chain slipping. On one side of each sheave is a spur-tooth wheel, as indicated at O and D, said wheels differing in diameter to an extent which will allow of a greater number of teeth being employed in one than is in the other, as shown in the drawings. These geared sheaves revolve loosely upon the pivot-pin J independently of each other.

The two spur-pinions E F on the shaft I differ in diameter and the number of their teeth, corresponding to the difference in diameter and number of teeth of the wheels G D. They are Xed on the shaft so as to revolve with it,"

and consequently both make a revolution in the same time. The pinion E gears with the wheel C, and the pinion F gears with the wheel D, thus making two pairs of wheels and pinions, and hence it will be understood that by each revolution of the pinions E F the wheels C D, with their respective ch ain-sheaves G H, will be rotated with speeds different one from the other, corresponding to the difference in the relative diameters of the respective pairs of toothed wheels and pinions 5 also, that both chain-sheaves will revolve in the same direction at the same time, either to the right or left, accordingly as the blocks are operated for hoisting or lowering.

The end ofthe pinion-shaftlexteuds through the frame of the block, so as to receive the sheave M, which is xed upon the shaft so as to give motion to it, and has its periphery grooved and the sides of the groove provided with projections spaced to correspond to the pitch ofthe links of the endless hand-chain N, to prevent the chain slipping.

The bottom or single-sheave block is in principle an ordinary single sheave block, its sheave turning loosely upon its pivotpin, grooved upon its periphery to fit the hoistingchain, the block-frame forming a guard for retaining the chain upon the shea-ve.

The hoisting-chain R is endless and of a sufficient length to give lthe desired range in the hoisting capacity of the blocks, and it is rove through them in a manner which may be explained as follows, (the chain being endless, it is necessary to have the blocks apart, and put them together piece by piece as the chain is rove through them First, place the chain through the bottom block, B, carry up the chain on one side in direction of the arrow l, Fig. l, passing it over the-sheave Gr ot' the top block, and down in direction of the arrow 2; second, carry up the chain on the other IOO side in direction of the arrow 3, passing it over the sheave H, and down in direction of the arrow 4.

A loop in the chain will thus be formed, as at O, whichwill increase or decrease in length, according as the blocks are operated for hoisting or lowering.

Although the difference in the motion of the two chain-sheaves G H of the top block, as herein described, is obtained by a difference in the diameters of the spur-wheels C D and the spur-pinons E F, it is manifest that the same result can be obtained by making the two chain-sheaves 'G H of different diameters, or by a difference in the diameters of both the chain-sheaves and tooth-wheels to the extent necessary to obtain the power and speed desired.

Let us now suppose the wheels and chainsheaves of the block put in motion by^pulling on the hand-chain N. It has been explained that the motion of the two chain-sheaves G H of the top block will differ one from the other, and as the hoisting-chain will be wound up by one faster than it will be wound oft' by the other the loop in the chain in which the bottom single sheave block is suspended will lengthen or shorten, and with it the bottom block, B, will be raised or lowered, according as the blocks are operated for hoisting or lowering.

I am aware of the Letters Patent of Pennybacker, dated April 17 187 7 No. 189,649, and of Weston, August 7, 1877, No. 194,019, and do not claim anything shown therein as my invention, which operates on a different principle and is carried 'into effect by a different combination of mechanism; but

What I claim as new isl. The improved differential-pulley apparatus, consisting of the double ltop block, A, lower single block, B, endless hoisting-chain R, differentially-moving spur-geared sheaves G H, spur-wheels C D, pinions E F, and shaft I, all combined and operated substantially as and for the purpose described.

2. The combination of the grooved chainwheel M, chain N, shaft I, pinions E F, spurgears G D, pulleys GH, blocks A and B, and chain It, rove through the pulleys as described, all substantially as and for the purpose set forth.

3. The spur-gear wheels C and D, of different diameters,in combination with the pinions E F, pulleys G H, sheave-block B, having' a single-sheave block, A, carrying the two pulleys G H, endless chain It, and shaft I, substantially as and for the purpose described.

ft. The combination of an upper double-pulley block, A, carrying differentially and inde pendently moving pulleys G and H, and a lower single-sheave block, B, and an endless chain, R, rove through the pulleys and sheave in the manner speciiied, all substantially as and for the purpose set forth.

l W. H. THOMPSON.

Witnessesz W. It. THOMPSON,

G. SHERMAN. 

